Pre-Case Assessment: Test Your Baseline Knowledge
Answer these questions before reviewing the case to assess your hemodynamic and cardiac physiology foundation
1
Cardiac output is the product of heart rate and stroke volume. In a patient with a heart rate of 96 bpm and CO of 2.97 L/min, what is the calculated stroke volume?
A) 45 mL
B) 31 mL
C) 52 mL
D) 62 mL
Correct Answer: B
Learning Point: CO = HR x SV, so SV = CO/HR = 2,970 mL/min / 96 beats/min = 31 mL/beat. A stroke volume of 31 mL is profoundly reduced (normal 60-100 mL). When HR is already compensatory and CO remains critically low, the problem is always stroke volume.
📚 Learn More: RHC Comprehensive Interpretation Guide
Learning Point: CO = HR x SV, so SV = CO/HR = 2,970 mL/min / 96 beats/min = 31 mL/beat. A stroke volume of 31 mL is profoundly reduced (normal 60-100 mL). When HR is already compensatory and CO remains critically low, the problem is always stroke volume.
📚 Learn More: RHC Comprehensive Interpretation Guide
2
Which echocardiographic parameter BEST reflects intrinsic myocardial relaxation independent of loading conditions?
A) Mitral E/A ratio
B) Mitral E velocity
C) e' (tissue Doppler annular velocity)
D) Deceleration time
Correct Answer: C
Learning Point: The e' velocity measured by tissue Doppler at the mitral annulus reflects intrinsic myocardial relaxation and is relatively load-independent. The E/A ratio can be "pseudonormalized" by elevated left atrial pressure, masking severe diastolic dysfunction. An e' <7 cm/s (septal) indicates severely impaired relaxation regardless of the E/A ratio.
📚 Learn More: Misleading Echocardiographic Findings in Infiltrative Cardiomyopathy
Learning Point: The e' velocity measured by tissue Doppler at the mitral annulus reflects intrinsic myocardial relaxation and is relatively load-independent. The E/A ratio can be "pseudonormalized" by elevated left atrial pressure, masking severe diastolic dysfunction. An e' <7 cm/s (septal) indicates severely impaired relaxation regardless of the E/A ratio.
📚 Learn More: Misleading Echocardiographic Findings in Infiltrative Cardiomyopathy
3
A pulmonary capillary wedge pressure (PCWP) of 30 mmHg with a mean PA pressure of 29 mmHg yields a transpulmonary gradient (TPG) near zero. What does this indicate about the pulmonary hypertension?
A) Combined pre- and post-capillary PH (CpcPH)
B) Isolated post-capillary PH (IpcPH, WHO Group 2)
C) Pulmonary arterial hypertension (PAH, WHO Group 1)
D) Chronic thromboembolic PH (WHO Group 4)
Correct Answer: B
Learning Point: A TPG near zero (mPAP - PCWP) and PVR near zero confirms isolated post-capillary pulmonary hypertension (IpcPH). The pulmonary vasculature is a passive conduit transmitting elevated left-sided filling pressures. There is no intrinsic pulmonary vascular disease. The PH will improve if left heart failure is treated.
📚 Learn More: RHC Comprehensive Interpretation Guide
Learning Point: A TPG near zero (mPAP - PCWP) and PVR near zero confirms isolated post-capillary pulmonary hypertension (IpcPH). The pulmonary vasculature is a passive conduit transmitting elevated left-sided filling pressures. There is no intrinsic pulmonary vascular disease. The PH will improve if left heart failure is treated.
📚 Learn More: RHC Comprehensive Interpretation Guide
4
In a patient with BSA 1.70 m² and cardiac output of 2.97 L/min, what is the cardiac index, and what clinical threshold does it fall below?
A) CI 2.50 L/min/m² -- below the heart failure threshold of 2.8
B) CI 2.20 L/min/m² -- at the cardiogenic shock threshold
C) CI 1.75 L/min/m² -- below the cardiogenic shock threshold of 2.2
D) CI 1.50 L/min/m² -- at the refractory shock threshold
Correct Answer: C
Learning Point: CI = CO/BSA = 2.97/1.70 = 1.75 L/min/m². The cardiogenic shock threshold is CI <2.2 L/min/m². This patient is well below it -- hemodynamically in cardiogenic shock territory despite an EF of ~45%. This EF-CI mismatch is the hallmark of infiltrative cardiomyopathy.
📚 Learn More: Misleading Echocardiographic Findings in Infiltrative Cardiomyopathy
Learning Point: CI = CO/BSA = 2.97/1.70 = 1.75 L/min/m². The cardiogenic shock threshold is CI <2.2 L/min/m². This patient is well below it -- hemodynamically in cardiogenic shock territory despite an EF of ~45%. This EF-CI mismatch is the hallmark of infiltrative cardiomyopathy.
📚 Learn More: Misleading Echocardiographic Findings in Infiltrative Cardiomyopathy
Case Presentation
An 84-year-old woman presented with decompensated heart failure requiring right heart catheterization. Baseline data: BSA 1.70 m², hemoglobin 9.7 g/dL, heart rate 96 bpm.
She failed intensive diuretic therapy, with creatinine rising from 2.0 to 4.5 mg/dL and blood pressure dropping, necessitating ICU transfer for a furosemide drip with levophed vasopressor support. Subsequent workup revealed:
- Nephrotic-range proteinuria (PCR 7.9 g/g)
- Abnormal serum free light chains (kappa/lambda ratio 5.37)
- Markedly elevated cardiac biomarkers (BNP >4,500; Troponin I 60 ng/mL)
- Echocardiographic findings consistent with infiltrative cardiomyopathy
Right Heart Catheterization Data
| Parameter | Measured Value | Normal Range |
|---|---|---|
| RA pressure | 12/11 (mean 11) mmHg | 0-5 mmHg |
| RV pressure | 35/13 mmHg | 15-30/0-8 mmHg |
| PA pressure | 35/24 (mean 29) mmHg | 15-30/4-12 (mean <20) |
| PCWP | 31/31 (mean ~30) mmHg | 6-12 mmHg |
| CO (thermodilution) | 2.97 L/min | 4-8 L/min |
| Cardiac Index | 1.75 L/min/m² | 2.5-4.0 L/min/m² |
| Stroke Volume | 31 mL | 60-100 mL |
| SVI (SV/BSA) | 18.2 mL/m² | 33-47 mL/m² |
| Qp/Qs | 1.0 | 1.0 |
Echocardiographic Data
| Parameter | Value | Normal (Female) |
|---|---|---|
| LVIDD | 5.1 cm | 3.8-5.2 cm |
| IVSD (septum) | 1.3 cm | 0.6-0.9 cm |
| LVPWD (posterior wall) | 1.2 cm | 0.6-0.9 cm |
| RWT | 0.47 | <0.42 |
| LV Mass Index | 153 g/m² | <95 g/m² |
| EF (biplane) | 52% | >55% |
| EF (A4C / A2C / Visual / FS) | 59% / 42% / 31% / 31% | -- |
| e' septal | 4 cm/s | >7 cm/s |
| E/e' septal | 37 | <14 |
| MV E velocity | 1.47 m/s | 0.6-1.0 m/s |
| E/A ratio | 1.3 | Variable |
| Deceleration time | 219 ms | 160-240 ms |
| AVA / Mean gradient | 1.9 cm² / 6 mmHg | Normal valve |
Laboratory Data
| Test | Value | Reference |
|---|---|---|
| Kappa FLC | 17.4 mg/L | 3.3-19.4 mg/L |
| Lambda FLC | 3.24 mg/L | 5.7-26.3 mg/L |
| Kappa/Lambda ratio | 5.37 | 0.26-1.65 |
| dFLC (kappa - lambda) | 14.2 mg/L | -- |
| BNP | >4,500 pg/mL | <100 pg/mL |
| Troponin I | 60 ng/mL | <0.04 ng/mL |
| Creatinine (baseline / peak) | 2.0 / 4.5 mg/dL | 0.6-1.2 mg/dL |
| PCR | 7.9 g/g | <0.2 g/g |
| ACR | 4.5 g/g | <0.03 g/g |
| Non-albumin protein (PCR - ACR) | 3.4 g/g (43% of total) | -- |
| HbA1c | 6.9% | <5.7% |
Urinalysis
| Finding | Result |
|---|---|
| RBC | 1-2/HPF |
| Leukocyte esterase | Negative |
| Hyaline casts | 5 (elevated) |
| Granular casts | 2 (elevated) |
| Specific gravity | 1.020-1.025 |
| Glucose | Trace |
Clinical Reasoning: Interpret the Hemodynamics
Now that you have reviewed the data, apply your knowledge to interpret the findings
5
This patient has an EF of ~45% but a cardiac index of 1.75 L/min/m² and SV of 31 mL. What is the BEST explanation for this EF-hemodynamic mismatch?
A) Measurement error -- the EF and CO were obtained at different times
B) Severe mitral regurgitation creating a falsely elevated EF
C) Infiltrative cardiomyopathy with a stiff, small-cavity ventricle ejecting a small absolute volume
D) Severe tricuspid regurgitation with falsely low thermodilution CO
Correct Answer: C
Learning Point: EF is a ratio (SV/EDV). In infiltrative cardiomyopathy, the ventricle is stiff with a small end-diastolic volume. A small stroke volume ejected from a small cavity produces a "preserved" ratio, but the absolute output is critically low. An EF of 45% that produces an SVI of 18.2 mL/m² (roughly half normal) is the hallmark of an infiltrative, small-cavity ventricle. The EF looks acceptable; the absolute output is not.
📚 Learn More: Misleading Echocardiographic Findings in Infiltrative Cardiomyopathy
Learning Point: EF is a ratio (SV/EDV). In infiltrative cardiomyopathy, the ventricle is stiff with a small end-diastolic volume. A small stroke volume ejected from a small cavity produces a "preserved" ratio, but the absolute output is critically low. An EF of 45% that produces an SVI of 18.2 mL/m² (roughly half normal) is the hallmark of an infiltrative, small-cavity ventricle. The EF looks acceptable; the absolute output is not.
📚 Learn More: Misleading Echocardiographic Findings in Infiltrative Cardiomyopathy
6
The echocardiographer reported the E/A ratio of 1.3 as "impaired relaxation." The e' septal is 4 cm/s and E/e' is 37. What is the correct assessment of diastolic function?
A) Grade I diastolic dysfunction (impaired relaxation) as reported
B) Grade II or higher -- the E/A is pseudonormalized by elevated LA pressure; the e' of 4 cm/s confirms severe impairment
C) Normal diastolic function -- E/A of 1.3 is within the normal range
D) Indeterminate -- deceleration time of 219 ms is normal, making classification impossible
Correct Answer: B
Learning Point: The E/A ratio can be "pseudonormalized" when elevated LA pressure pushes the E wave back up despite impaired relaxation. An e' of 4 cm/s means the myocardium is relaxing at less than half the normal rate. An E/e' of 37 predicts severely elevated filling pressures, confirmed invasively (PCWP 30 mmHg). Always check tissue Doppler before accepting an E/A-based diastolic assessment.
📚 Learn More: Misleading Echocardiographic Findings in Infiltrative Cardiomyopathy
Learning Point: The E/A ratio can be "pseudonormalized" when elevated LA pressure pushes the E wave back up despite impaired relaxation. An e' of 4 cm/s means the myocardium is relaxing at less than half the normal rate. An E/e' of 37 predicts severely elevated filling pressures, confirmed invasively (PCWP 30 mmHg). Always check tissue Doppler before accepting an E/A-based diastolic assessment.
📚 Learn More: Misleading Echocardiographic Findings in Infiltrative Cardiomyopathy
7
The EF values across methods range from 31% (visual/FS) to 59% (A4C). What does this wide variability across methods suggest?
A) Poor image quality requiring contrast echocardiography
B) Operator-dependent variability without clinical significance
C) Regional variation in function -- apical segments contracting while basal/mid segments are impaired (apical sparing pattern)
D) Tachycardia-mediated measurement artifact at HR 96
Correct Answer: C
Learning Point: A spread of 31-59% across EF methods is itself abnormal and suggests regional variation in contractility. In cardiac amyloidosis, amyloid infiltration typically affects basal and mid segments first, sparing the apex. This produces the classic "apical sparing" pattern on strain imaging, and causes different views and methods to yield widely discrepant EF values depending on which segments are captured.
📚 Learn More: Misleading Echocardiographic Findings in Infiltrative Cardiomyopathy
Learning Point: A spread of 31-59% across EF methods is itself abnormal and suggests regional variation in contractility. In cardiac amyloidosis, amyloid infiltration typically affects basal and mid segments first, sparing the apex. This produces the classic "apical sparing" pattern on strain imaging, and causes different views and methods to yield widely discrepant EF values depending on which segments are captured.
📚 Learn More: Misleading Echocardiographic Findings in Infiltrative Cardiomyopathy
8
The RA mean pressure is 11 mmHg and PCWP is 30 mmHg, giving a 19 mmHg gradient. How should this be interpreted in the context of possible infiltrative disease?
A) This excludes restrictive/infiltrative cardiomyopathy, which requires equalization of filling pressures
B) This confirms biventricular failure without infiltrative disease
C) This is consistent with left-dominant or asymmetric infiltration where the LV is more heavily involved; equalization is a late finding
D) This pattern is diagnostic of pericardial constriction rather than restriction
Correct Answer: C
Learning Point: The 19 mmHg gradient initially argues against classic restriction, but does NOT exclude infiltrative disease. Left-dominant or asymmetric infiltration -- where the LV is more heavily involved than the RV -- produces exactly this pattern. Classic equalization of filling pressures is a late finding that occurs only when both ventricles are equally stiff. Do not use the absence of equalization to rule out amyloid.
📚 Learn More: Restrictive vs Constrictive Physiology
Learning Point: The 19 mmHg gradient initially argues against classic restriction, but does NOT exclude infiltrative disease. Left-dominant or asymmetric infiltration -- where the LV is more heavily involved than the RV -- produces exactly this pattern. Classic equalization of filling pressures is a late finding that occurs only when both ventricles are equally stiff. Do not use the absence of equalization to rule out amyloid.
📚 Learn More: Restrictive vs Constrictive Physiology
Interactive Timeline: Clinical Decision Points
Walk through the key management decisions in this patient's course
Decision Point 1: The patient fails diuresis with creatinine doubling and hypotension. What does the need for vasopressor-supported diuresis tell you?
Key Insight: With CO fixed at ~3 L/min (MAP = CO x TPR), diuresis drops preload, SV falls, CO falls, MAP falls, and AKI ensues. Levophed raises TPR to maintain MAP, enabling continued diuresis. This preload dependence is diagnostic: a dilated cardiomyopathy improves with preload reduction, but an infiltrative cardiomyopathy operates on a flat Starling curve where any preload reduction drops output precipitously. The stiff ventricle needs high filling pressures for its meager output.
📚 Learn More: RHC in Amyloidosis: Hemodynamic Patterns
📚 Learn More: RHC in Amyloidosis: Hemodynamic Patterns
9
When should serum free light chains be ordered in this clinical scenario?
A) Only after tissue biopsy confirms amyloid deposits
B) Only if SPEP shows a visible M-protein band
C) Immediately when infiltrative cardiomyopathy is suspected -- FLC ratio can be abnormal even when SPEP is negative
D) After PYP scan confirms ATTR amyloidosis
Correct Answer: C
Learning Point: The Mayo serum monoclonal screen can be negative for M-protein while the FLC ratio is abnormal. Even fully negative serum AND urine protein electrophoresis miss 10-15% of AL amyloidosis patients, who are diagnosed solely on abnormal FLC ratio plus tissue confirmation. FLC should be ordered at the first suspicion of infiltrative disease.
📚 Learn More: Monoclonal Protein Interpretation for the Nephrologist
Learning Point: The Mayo serum monoclonal screen can be negative for M-protein while the FLC ratio is abnormal. Even fully negative serum AND urine protein electrophoresis miss 10-15% of AL amyloidosis patients, who are diagnosed solely on abnormal FLC ratio plus tissue confirmation. FLC should be ordered at the first suspicion of infiltrative disease.
📚 Learn More: Monoclonal Protein Interpretation for the Nephrologist
Decision Point 2: You discover nephrotic-range proteinuria. When should you compare ACR and PCR?
Key Insight: Always order ACR and PCR simultaneously. The cost is minimal, and the comparison is diagnostic. In this patient, PCR = 7.9 g/g and ACR = 4.5 g/g. The non-albumin fraction is 3.4 g/g (43% of total protein). An albumin fraction below 60% indicates significant non-albumin proteinuria -- and the most common cause of large-volume non-albumin proteinuria is free light chain excretion. This is the cheapest screening maneuver for light chain renal involvement.
📚 Learn More: Nephrotic Syndrome Presenting as Heart Failure
📚 Learn More: Nephrotic Syndrome Presenting as Heart Failure
10
At what point should tissue biopsy be considered to confirm amyloidosis in a patient with this presentation?
A) Only after starting empiric chemotherapy to assess response
B) Once non-invasive data (abnormal FLC, infiltrative echo, elevated biomarkers) converge -- tissue confirmation with Congo red staining is required before treatment
C) Biopsy is unnecessary if the PYP scan is positive
D) Biopsy should be deferred until renal function recovers to baseline
Correct Answer: B
Learning Point: AL amyloidosis requires tissue confirmation with Congo red staining showing apple-green birefringence under polarized light, followed by mass spectrometry typing. A positive PYP scan with NO monoclonal protein can confirm ATTR without biopsy, but ANY abnormal FLC ratio or M-protein mandates tissue biopsy to exclude AL (which requires urgent chemotherapy). Treatment decisions hinge on accurate typing.
📚 Learn More: AL Amyloidosis and Multiple Myeloma
Learning Point: AL amyloidosis requires tissue confirmation with Congo red staining showing apple-green birefringence under polarized light, followed by mass spectrometry typing. A positive PYP scan with NO monoclonal protein can confirm ATTR without biopsy, but ANY abnormal FLC ratio or M-protein mandates tissue biopsy to exclude AL (which requires urgent chemotherapy). Treatment decisions hinge on accurate typing.
📚 Learn More: AL Amyloidosis and Multiple Myeloma
11
This patient's diuretic resistance with hemodynamic collapse is best managed by which approach?
A) Increasing the loop diuretic dose to overcome resistance
B) Adding a thiazide diuretic for sequential nephron blockade
C) Vasopressor support to maintain MAP while cautiously diuresing, accepting higher filling pressures than in typical HF
D) Urgent ultrafiltration to remove volume independent of hemodynamics
Correct Answer: C
Learning Point: In infiltrative cardiomyopathy, the heart operates on a flat Starling curve. Output is fixed at a small SV, and any preload reduction drops output precipitously. MAP = CO x TPR; with CO fixed, vasopressors raise TPR to maintain MAP. The goal is gentle volume removal while maintaining perfusion -- not aggressive decongestion. These patients require higher filling pressures for their meager output. Aggressive diuresis or UF without hemodynamic support will cause cardiogenic shock.
📚 Learn More: Nephrotic Syndrome Presenting as Heart Failure
Learning Point: In infiltrative cardiomyopathy, the heart operates on a flat Starling curve. Output is fixed at a small SV, and any preload reduction drops output precipitously. MAP = CO x TPR; with CO fixed, vasopressors raise TPR to maintain MAP. The goal is gentle volume removal while maintaining perfusion -- not aggressive decongestion. These patients require higher filling pressures for their meager output. Aggressive diuresis or UF without hemodynamic support will cause cardiogenic shock.
📚 Learn More: Nephrotic Syndrome Presenting as Heart Failure
12
The urine sediment shows hyaline casts (5) and granular casts (2) with minimal hematuria. What does this sediment pattern indicate about the cause of AKI?
A) Active glomerulonephritis requiring urgent biopsy
B) Acute interstitial nephritis from medication exposure
C) Cardiorenal AKI with superimposed ischemic tubular injury from low cardiac output
D) Cast nephropathy from light chain precipitation in tubules
Correct Answer: C
Learning Point: Hyaline casts indicate prerenal/low-flow physiology. Granular casts indicate tubular injury. The combination tells a coherent story: cardiorenal AKI (CI 1.75, inadequate renal perfusion) with superimposed ischemic acute tubular injury from diuresis-induced further perfusion loss. The absence of significant hematuria argues against active GN. This is not primary renal disease -- treating the kidney means treating the heart.
📚 Learn More: Nephrotic Syndrome Presenting as Heart Failure
Learning Point: Hyaline casts indicate prerenal/low-flow physiology. Granular casts indicate tubular injury. The combination tells a coherent story: cardiorenal AKI (CI 1.75, inadequate renal perfusion) with superimposed ischemic acute tubular injury from diuresis-induced further perfusion loss. The absence of significant hematuria argues against active GN. This is not primary renal disease -- treating the kidney means treating the heart.
📚 Learn More: Nephrotic Syndrome Presenting as Heart Failure
Module Deep Dive: Amyloidosis Pathophysiology and Staging
Test your knowledge of amyloid biology, FLC interpretation, and prognostic staging
13
This patient has kappa FLC 17.4 mg/L, lambda FLC 3.24 mg/L, ratio 5.37, with creatinine 4.5 mg/dL. A colleague argues the abnormal ratio is due to CKD retention. What is the BEST counter-argument?
A) The ratio exceeds the standard normal range upper limit of 1.65
B) The kappa FLC is above the upper limit of normal
C) CKD elevates both chains proportionally; a suppressed lambda of 3.24 mg/L with a ratio exceeding the CKD-adjusted threshold of 3.1 indicates clonal suppression, not renal retention
D) FLC assays are unreliable in the setting of AKI
Correct Answer: C
Learning Point: Three key arguments: (1) The ratio of 5.37 exceeds the CKD-adjusted threshold of 3.1. (2) Lambda is LOW-NORMAL (3.24 mg/L, near the floor of the normal range), not elevated. In CKD retention, both chains should be elevated. (3) CKD elevates both chains proportionally; it does not suppress one. A suppressed uninvolved chain with an elevated involved chain is the signature of clonal biology -- a monoclonal kappa-producing plasma cell clone is crowding out normal immunoglobulin production.
📚 Learn More: Monoclonal Protein Interpretation for the Nephrologist
Learning Point: Three key arguments: (1) The ratio of 5.37 exceeds the CKD-adjusted threshold of 3.1. (2) Lambda is LOW-NORMAL (3.24 mg/L, near the floor of the normal range), not elevated. In CKD retention, both chains should be elevated. (3) CKD elevates both chains proportionally; it does not suppress one. A suppressed uninvolved chain with an elevated involved chain is the signature of clonal biology -- a monoclonal kappa-producing plasma cell clone is crowding out normal immunoglobulin production.
📚 Learn More: Monoclonal Protein Interpretation for the Nephrologist
14
Using the Mayo 2012 Revised Staging System for AL amyloidosis, this patient has BNP >4,500, Troponin I 60 ng/mL, and dFLC 14.2 mg/L. What is the stage and approximate prognosis?
A) Stage II (1 point: troponin only) -- median survival 12-18 months
B) Stage IIIa (2 points: BNP + troponin, dFLC <180) -- median survival 6-12 months with treatment
C) Stage IIIb (3 points: all three thresholds met) -- median survival <6 months
D) Stage IV -- requiring mechanical circulatory support
Correct Answer: B
Learning Point: Mayo 2012 thresholds: NT-proBNP ≥1,800 pg/mL (or BNP equivalent), cTnI ≥0.1 ng/mL, dFLC ≥180 mg/L. This patient scores 1 for BNP (>4,500) and 1 for troponin (60 ng/mL), but 0 for dFLC (14.2 mg/L, well below 180). Total = 2 points = Stage IIIa. Median survival with treatment is approximately 6-12 months. Without treatment, 3-4 months. The sub-classification of IIIa vs IIIb depends on NT-proBNP above or below 8,500 pg/mL.
📚 Learn More: Cardiac-Predominant AL Amyloidosis
Learning Point: Mayo 2012 thresholds: NT-proBNP ≥1,800 pg/mL (or BNP equivalent), cTnI ≥0.1 ng/mL, dFLC ≥180 mg/L. This patient scores 1 for BNP (>4,500) and 1 for troponin (60 ng/mL), but 0 for dFLC (14.2 mg/L, well below 180). Total = 2 points = Stage IIIa. Median survival with treatment is approximately 6-12 months. Without treatment, 3-4 months. The sub-classification of IIIa vs IIIb depends on NT-proBNP above or below 8,500 pg/mL.
📚 Learn More: Cardiac-Predominant AL Amyloidosis
15
Concentric LVH with normal cavity size, no aortic stenosis, and wall thickness of 1.3 cm in an 84-year-old woman with heart failure. Which diagnostic pathway is MOST appropriate?
A) Assume hypertensive heart disease given the patient's age and start antihypertensives
B) Order cardiac MRI with late gadolinium enhancement as the sole diagnostic test
C) Order FLC, SPEP/UPEP with immunofixation, and PYP scan to differentiate AL from ATTR amyloidosis
D) Proceed directly to endomyocardial biopsy without non-invasive testing
Correct Answer: C
Learning Point: Concentric hypertrophy (thick walls, normal cavity) in a non-hypertensive patient has a short differential: hypertensive heart disease, aortic stenosis, and infiltrative cardiomyopathy. With a normal aortic valve (AVA 1.9 cm²), the pattern demands evaluation for amyloid. The critical first step is differentiating AL from ATTR: FLC + SPEP/UPEP screens for monoclonal protein; PYP scan identifies ATTR. A positive PYP with no monoclonal protein = ATTR without biopsy. Any monoclonal protein = must biopsy to exclude AL. Diagnostic delays average 13 months with 44% initial misdiagnosis rates.
📚 Learn More: ATTR Cardiac Amyloidosis
Learning Point: Concentric hypertrophy (thick walls, normal cavity) in a non-hypertensive patient has a short differential: hypertensive heart disease, aortic stenosis, and infiltrative cardiomyopathy. With a normal aortic valve (AVA 1.9 cm²), the pattern demands evaluation for amyloid. The critical first step is differentiating AL from ATTR: FLC + SPEP/UPEP screens for monoclonal protein; PYP scan identifies ATTR. A positive PYP with no monoclonal protein = ATTR without biopsy. Any monoclonal protein = must biopsy to exclude AL. Diagnostic delays average 13 months with 44% initial misdiagnosis rates.
📚 Learn More: ATTR Cardiac Amyloidosis
16
The urine protein pattern shows PCR 7.9 g/g with ACR 4.5 g/g (albumin fraction 57%). What is the significance of this ACR/PCR dissociation?
A) This is a lab error -- ACR should always equal PCR in nephrotic syndrome
B) The non-albumin fraction represents tubular protein from AKI only
C) 43% non-albumin proteinuria strongly suggests free light chain excretion; albumin fraction <60% indicates significant overflow proteinuria
D) This pattern is typical of diabetic nephropathy with concurrent tubular dysfunction
Correct Answer: C
Learning Point: In pure glomerular disease, the albumin fraction is typically >80%. A fraction <60% indicates significant non-albumin proteinuria, and the most common cause of large-volume non-albumin proteinuria is free light chain excretion. This simple comparison (ordering both ACR and PCR) is the cheapest screening maneuver for detecting light chain renal involvement. Pattern guide: >80% = pure glomerular; 60-80% = mixed; <60% = significant overflow or tubular; <30% = predominantly overflow.
📚 Learn More: Nephrotic Syndrome Presenting as Heart Failure
Learning Point: In pure glomerular disease, the albumin fraction is typically >80%. A fraction <60% indicates significant non-albumin proteinuria, and the most common cause of large-volume non-albumin proteinuria is free light chain excretion. This simple comparison (ordering both ACR and PCR) is the cheapest screening maneuver for detecting light chain renal involvement. Pattern guide: >80% = pure glomerular; 60-80% = mixed; <60% = significant overflow or tubular; <30% = predominantly overflow.
📚 Learn More: Nephrotic Syndrome Presenting as Heart Failure
Learning Objectives: Verification
Objective 1: Recognize the hemodynamic-EF mismatch as a cardinal sign of infiltrative cardiomyopathy
Objective 2: Correctly interpret tissue Doppler parameters (e') over E/A ratio for diastolic assessment
Objective 3: Apply CKD-adjusted FLC interpretation to distinguish clonal disease from renal retention
Objective 4: Use ACR/PCR dissociation to screen for free light chain proteinuria
Objective 5: Stage AL amyloidosis using the Mayo 2012 Revised System
Objective 6: Understand diuretic resistance as a diagnostic clue to infiltrative physiology, not a failure of therapy
Learning Objectives: Verification Questions
Confirm you have achieved the learning objectives from this case
17
A patient with EF 50%, CI 1.9, BNP 3,200, and concentric LVH fails diuresis with hemodynamic collapse. Which single statement BEST captures the unifying diagnosis?
A) This is HFpEF with typical diuretic resistance due to volume-dependent diastolic filling
B) The EF-CI mismatch with diuretic intolerance indicates a stiff, infiltrated ventricle that cannot generate adequate stroke volume from its small cavity
C) This is right heart failure with preserved left ventricular function
D) This represents acute myocarditis with transient hemodynamic compromise
Correct Answer: B
Learning Point: The three converging clues -- (1) EF-CI mismatch (preserved EF, critically low CI), (2) concentric LVH without AS or longstanding hypertension, and (3) diuretic intolerance from flat Starling physiology -- are the hallmarks of infiltrative cardiomyopathy. A patient who "should" tolerate diuresis but doesn't is a patient whose ventricle is stiffer than the EF suggests. This presentation demands an immediate amyloid workup.
📚 Learn More: Misleading Echocardiographic Findings in Infiltrative Cardiomyopathy
Learning Point: The three converging clues -- (1) EF-CI mismatch (preserved EF, critically low CI), (2) concentric LVH without AS or longstanding hypertension, and (3) diuretic intolerance from flat Starling physiology -- are the hallmarks of infiltrative cardiomyopathy. A patient who "should" tolerate diuresis but doesn't is a patient whose ventricle is stiffer than the EF suggests. This presentation demands an immediate amyloid workup.
📚 Learn More: Misleading Echocardiographic Findings in Infiltrative Cardiomyopathy
18
Which of the following is TRUE regarding the role of a negative SPEP in excluding AL amyloidosis?
A) A negative SPEP excludes AL amyloidosis with >99% sensitivity
B) A negative SPEP with a normal FLC ratio excludes AL amyloidosis
C) A negative SPEP does NOT exclude AL -- 10-15% of AL patients are diagnosed solely on abnormal FLC ratio plus tissue confirmation
D) SPEP is no longer recommended in the workup of suspected amyloidosis
Correct Answer: C
Learning Point: The Mayo serum monoclonal screen can be negative for M-protein while the FLC ratio from the same panel is abnormal. Even fully negative serum AND urine protein electrophoresis miss 10-15% of AL patients. The FLC ratio is the most sensitive single test for detecting monoclonal light chains. Any abnormal FLC ratio in the setting of suspected amyloidosis mandates tissue biopsy regardless of SPEP result.
📚 Learn More: Monoclonal Protein Interpretation for the Nephrologist
Learning Point: The Mayo serum monoclonal screen can be negative for M-protein while the FLC ratio from the same panel is abnormal. Even fully negative serum AND urine protein electrophoresis miss 10-15% of AL patients. The FLC ratio is the most sensitive single test for detecting monoclonal light chains. Any abnormal FLC ratio in the setting of suspected amyloidosis mandates tissue biopsy regardless of SPEP result.
📚 Learn More: Monoclonal Protein Interpretation for the Nephrologist
Integration Challenge: Multi-System Synthesis
These questions require integrating cardiac, renal, and hematologic data simultaneously
19
An 84-year-old presents with decompensated HF (CI 1.75, PCWP 30), AKI (Cr 2.0 to 4.5), nephrotic proteinuria (PCR 7.9, ACR 4.5), FLC ratio 5.37 with suppressed lambda, and concentric LVH with e' of 4. Which differential diagnosis BEST explains ALL findings simultaneously?
A) Diabetic nephropathy with HFpEF and incidental monoclonal gammopathy of undetermined significance
B) AL amyloidosis with cardiac infiltration (causing HF, low CI, elevated biomarkers), renal amyloid deposition (causing proteinuria), and cardiorenal AKI from low output
C) ATTR amyloidosis with concurrent diabetic nephropathy
D) Hypertensive cardiomyopathy with FSGS and reactive FLC elevation from CKD
Correct Answer: B
Learning Point: AL amyloidosis is the only diagnosis that unifies ALL findings: (1) Cardiac infiltration explains the concentric LVH, EF-CI mismatch, e' of 4, E/e' of 37, elevated biomarkers, and diuretic resistance. (2) Renal amyloid deposition explains the nephrotic proteinuria with the non-albumin gap (light chains). (3) Low cardiac output explains the cardiorenal AKI. (4) The abnormal FLC ratio with suppressed lambda confirms clonal disease. ATTR would not explain the FLC abnormality or proteinuria. Diabetic nephropathy would not explain the EF-CI mismatch or non-albumin protein gap.
📚 Learn More: AL Amyloidosis and Multiple Myeloma
Learning Point: AL amyloidosis is the only diagnosis that unifies ALL findings: (1) Cardiac infiltration explains the concentric LVH, EF-CI mismatch, e' of 4, E/e' of 37, elevated biomarkers, and diuretic resistance. (2) Renal amyloid deposition explains the nephrotic proteinuria with the non-albumin gap (light chains). (3) Low cardiac output explains the cardiorenal AKI. (4) The abnormal FLC ratio with suppressed lambda confirms clonal disease. ATTR would not explain the FLC abnormality or proteinuria. Diabetic nephropathy would not explain the EF-CI mismatch or non-albumin protein gap.
📚 Learn More: AL Amyloidosis and Multiple Myeloma
20
Integrating all available data, rank the differential diagnoses for this patient from most to least likely:
A) AL amyloidosis > LCDD > ATTR + concurrent glomerular disease > diabetic nephropathy + HFpEF > hypertensive cardiomyopathy
B) ATTR amyloidosis > AL amyloidosis > hypertensive cardiomyopathy > diabetic nephropathy > LCDD
C) Diabetic nephropathy + HFpEF > AL amyloidosis > ATTR > LCDD > hypertensive cardiomyopathy
D) Hypertensive cardiomyopathy > ATTR > diabetic nephropathy > AL amyloidosis > LCDD
Correct Answer: A
Learning Point: AL amyloidosis leads because it explains the FLC ratio 5.37 with suppressed lambda, 43% non-albumin proteinuria, EF-CI mismatch, concentric LVH with e' of 4, extreme biomarker elevation, and diuretic resistance. LCDD is second as it can produce similar FLC and renal findings but typically causes less cardiac involvement. ATTR is possible at age 84 (peak for ATTRwt) but does not explain the FLC abnormality or proteinuria pattern. Diabetic nephropathy + HFpEF does not explain the non-albumin gap, EF-CI mismatch, or SV of 31 mL. Hypertensive heart disease does not produce wall thickness of 1.3 cm, e' of 4, or this proteinuria pattern.
📚 Learn More: Nephrotic Syndrome Presenting as Heart Failure
Learning Point: AL amyloidosis leads because it explains the FLC ratio 5.37 with suppressed lambda, 43% non-albumin proteinuria, EF-CI mismatch, concentric LVH with e' of 4, extreme biomarker elevation, and diuretic resistance. LCDD is second as it can produce similar FLC and renal findings but typically causes less cardiac involvement. ATTR is possible at age 84 (peak for ATTRwt) but does not explain the FLC abnormality or proteinuria pattern. Diabetic nephropathy + HFpEF does not explain the non-albumin gap, EF-CI mismatch, or SV of 31 mL. Hypertensive heart disease does not produce wall thickness of 1.3 cm, e' of 4, or this proteinuria pattern.
📚 Learn More: Nephrotic Syndrome Presenting as Heart Failure
Key Teaching Points Summary
Teaching Point 1 -- Hemodynamic-EF Mismatch
CI 1.75 with EF 45% is the central clue to infiltrative cardiomyopathy. An EF that "looks fine" but produces terrible hemodynamics should trigger an infiltrative workup.
Teaching Point 2 -- Tissue Doppler Trumps E/A
An e' of 4 cm/s with E/e' of 37 represents severe diastolic impairment regardless of what the E/A ratio suggests. Always check tissue Doppler before accepting E/A-based diastolic assessment.
Teaching Point 3 -- FLC Ratio in CKD
CKD elevates both chains proportionally; it does not suppress one. A ratio of 5.37 with a suppressed uninvolved chain exceeds the CKD-adjusted threshold (3.1) and represents clonal biology, not renal physiology.
Teaching Point 4 -- Urine Protein Composition
Ordering both ACR and PCR simultaneously and comparing them reveals the non-albumin fraction. An albumin fraction <60% suggests overflow proteinuria (light chains) -- the cheapest screening maneuver for light chain renal involvement.
Teaching Point 5 -- Negative Monoclonal Screen Does Not Exclude Disease
The Mayo serum monoclonal screen can be negative for M-protein while the FLC ratio from the same panel is abnormal. Even fully negative serum AND urine studies miss 10-15% of AL patients, who are diagnosed solely on abnormal FLC ratio plus tissue confirmation.
Teaching Point 6 -- Cardiac Amyloidosis Mimics HFpEF
Diagnostic delays average 13 months, with 44% initial misdiagnosis rates. Concentric LVH with normal cavity, depressed e', and disproportionate hemodynamic compromise should trigger the diagnostic algorithm.
Diuretic Resistance as a Diagnostic Clue
In any patient where diuresis causes hemodynamic collapse despite only mildly reduced EF, think infiltrative disease. The dilated cardiomyopathy improves with preload reduction; the infiltrative cardiomyopathy operates on a flat Starling curve and crashes with any preload reduction. The heart that "should" tolerate diuresis but doesn't is stiffer than its EF suggests.
Hemodynamic Equations Reference
Equation 1: Cardiac Output = Heart Rate x Stroke Volume
CO = HR x SV = 96 x 0.031 = 2.97 L/min
Heart rate is 96 -- already compensating. Despite this, CO is critically low because SV is catastrophically reduced at 31 mL.
Equation 2: MAP = Cardiac Output x Total Peripheral Resistance
MAP = CO x TPR
With CO fixed at ~3 L/min, MAP depends entirely on TPR. Diuresis drops preload, SV falls, CO falls, MAP falls, AKI ensues. Levophed raises TPR to maintain MAP, enabling diuresis.
Pulmonary Hypertension Classification
| Derived Parameter | Calculation | Value | Interpretation |
|---|---|---|---|
| TPG | mPAP - PCWP | 29 - 30 = ~0 mmHg | No pre-capillary disease |
| DPG | PA diastolic - PCWP | 24 - 30 = -6 mmHg | No remodeling |
| PVR | (mPAP - PCWP)/CO | ~0/2.97 = ~0 WU | Normal pulmonary vasculature |
Structured Differential Comparison
| Diagnosis | Supporting Evidence | Arguing Against |
|---|---|---|
| AL amyloidosis (leading) | FLC ratio 5.37, suppressed lambda, 43% non-albumin proteinuria, EF-CI mismatch, concentric LVH with normal cavity, e' of 4, E/e' 37, BNP >4,500, TnI 60, diuretic resistance | Mayo serum monoclonal screen negative for M-protein (but FLC ratio abnormal); urine studies pending |
| Diabetic nephropathy + HFpEF | A1c 6.9, nephrotic proteinuria, age | Does not explain non-albumin protein gap, EF-CI mismatch, SV of 31 mL, or e' of 4 |
| ATTR amyloidosis | Age 84 (peak for ATTRwt), concentric LVH, HF | Would not explain abnormal FLC ratio or proteinuria; PYP scan differentiates |
| LCDD | Similar FLC pattern, nephrotic syndrome possible | Less cardiac involvement typically, Congo red may be negative |
| Hypertensive heart disease | Common cause of LVH in elderly | Does not produce wall thickness of 1.3 cm, e' of 4, or this urine protein pattern |
Selected References
- Falk RH, et al. AL (Light-Chain) Cardiac Amyloidosis: A Review. JACC. 2016;68(12):1323-1341.
- Garcia-Pavia P, et al. Diagnosis and Treatment of Cardiac Amyloidosis. Eur Heart J. 2021;42(16):1554-1568.
- Nagueh SF, et al. Recommendations for Evaluation of LV Diastolic Function. J Am Soc Echocardiogr. 2016;29(4):277-314.
- Hutchison CA, et al. Polyclonal Free Light Chains in CKD. CJASN. 2008;3(6):1684-1690.
- Dispenzieri A, et al. IMWG Guidelines for Serum-Free Light Chain Analysis. Leukemia. 2009;23(2):215-224.
- Kumar S, et al. Revised Prognostic Staging for AL Amyloidosis. J Clin Oncol. 2012;30(9):989-995.
- Kastritis E, et al. Daratumumab-Based Treatment for AL Amyloidosis (ANDROMEDA). N Engl J Med. 2021;385(1):46-58.
- Ronco C, et al. Cardio-Renal Syndromes. Eur Heart J. 2010;31(6):703-711.